Peregrine Pharmaceuticals updates on Bavituximab breast cancer study

Jun 2 2008

Peregrine Pharmaceuticals, Inc. has announced that results from a Phase I clinical trial of its lead anti-phosphatidylserine (anti-PS) antibody bavituximab in combination with chemotherapy in patients with advanced cancer were presented at the American Society of Clinical Oncology (ASCO) Annual Meeting.

The Phase I data indicated that half of evaluable patients in the trial achieved objective tumor response or stable disease after eight weeks of dosing. The Phase I study results also showed that the safety profile of bavituximab and chemotherapy appeared consistent with chemotherapy alone and that the pharmacokinetic properties of bavituximab were not impacted by co- administration with conventional chemotherapies.

Separately, Peregrine reported an update from its ongoing Phase II trial evaluating bavituximab plus docetaxel in advanced breast cancer. Enrollment of an initial group of 15 patients in the two-stage Phase II study was recently completed. Of the 11 evaluable patients to date, none have experienced any measureable tumor growth or disease progression, with five of the 11 evaluable patients achieving a partial tumor response. All enrolled patients are continuing to receive treatment and are being evaluated regularly for tumor response according to RECIST criteria. The primary objective of the multi-center, open label study is to assess overall tumor response rate, and the study may be expanded to a total of 46 subjects following complete evaluation of data from the first 15 patients.

"Bavituximab represents a completely novel approach to treating cancer that helps mobilize the body's own immune system to attack tumors and the blood vessels supporting tumor growth and spread," said Dr. Raghunadharao Digumarti, professor of medical oncology at the Nizams Institute of Medical Sciences in Hyderabad, India, and a principal investigator of the Phase I clinical trial presented at ASCO. "We believe these encouraging study results support the upcoming Phase II safety and efficacy trials of bavituximab in breast and lung cancers that we look forward to participating in."

The open label, multi-center Phase I study was conducted in patients with refractory advanced solid tumors. The study objectives were to assess the safety and tolerability of bavituximab and to characterize its pharmacokinetic profile when used in combination with standard chemotherapy. Patients received up to eight weekly doses of bavituximab in combination with docetaxel, gemcitabine or paclitaxel plus carboplatin.

"The opportunity to share the positive results of the Phase I clinical study at ASCO provides us with a great platform to inform the broader oncology community about the potential of bavituximab and our anti-PS technology," said Steven W. King, president and CEO of Peregrine. "The promising anti-tumor activity of bavituximab in combination with chemotherapy seen in the Phase I and Phase II studies to date are encouraging, and we look forward to reporting additional results in the coming months."

Bavituximab is a monoclonal antibody that binds to the cellular membrane component PS that is usually located inside cells, but which becomes exposed on the outside of the cells that line the blood vessels of tumors, creating a specific target for anti-cancer treatments. By binding to PS, bavituximab is believed to help mobilize the body's immune system to destroy the tumor and the tumor blood vessels. Bavituximab currently is in a Phase II combination therapy trial for the treatment of advanced breast cancer and additional Phase II trials in non-small cell lung cancer (NSCLC) and breast cancer are expected to begin soon. A Phase I bavituximab monotherapy trial in advanced solid cancers is continuing.